Straightforward access to enantiomerically enriched cis-3-benzyl-chromanols from (E)-3-benzylidene-chromanones was developed through Rh-catalyzed asymmetric transfer hydrogenation. This transformation allowed the reduction of both the CC and CO bonds and the formation of two stereocenters in high yields with excellent levels of diastereo- and enantioselectivities (up to >99:1 dr, up to >99% ee) in a single step through a dynamic kinetic resolution process using a low catalyst loading and HCO2H/DABCO as the hydrogen source.

Based on the ever-increasing demand for enantiomerically pure compounds, the development of efficient, atom-economical, and sustainable methods to produce chiral alcohols and amines is a major concern. Homogeneous asymmetric catalysis with transition-metal complexes including asymmetric hydrogenation (AH) and transfer hydrogenation (ATH) of ketones and imines through dynamic kinetic resolution (DKR) allowing the construction of up to three stereogenic centers is the main focus of the present short review, emphasizing the development of new catalytic systems combined to new classes of substrates and their applications as well.1 Introduction2 Asymmetric Hydrogenation via Dynamic Kinetic Resolution2.1 α-Substituted Ketones2.2 α-Substituted β-Keto Esters and Amides2.3 α-Substituted Esters2.4 Imine Derivatives3 Asymmetric Transfer Hydrogenation via Dynamic Kinetic Resolution3.1 α-Substituted Ketones3.2 α-Substituted β-Keto Esters, Amides, and Sulfonamides3.3 α,β-Disubstituted Cyclic Ketones3.4 β-Substituted Ketones3.5 Imine Derivatives4. Conclusion

Enantioenriched cis-3-fluoro-chroman-4-ol derivatives were conveniently prepared by the ruthenium-catalyzed asymmetric transfer hydrogenation of a new family of 3-fluoro-chromanones through a dynamic kinetic resolution process. The reaction proceeded under mild conditions using a low catalyst loading and HCO 2 H/Et 3 N (1:1) as the hydrogen source, affording the reduced fluorinated alcohols in good yields (80−96%), high diastereomeric ratios (up to 99:1 dr), and excellent enantioselectivities (up to >99% ee).